HAL: Do not limit HAL command argument length unnecessarily.

The length of any single token in HAL is limited to LINELEN (255 chars)
even though line continuation support means that individual commands can
be up to MAX_EXTEND_LINES (20) times this length.
This patch increments the buffer size by LINELEN until there is plenty of
space (to allow for tilde expansion)
Fixes #3098

Author: andypugh

docs/src/man/man1/mqtt-publisher.1.adoc

@@ -100,24 +100,21 @@ loadusr -W mqtt-publisher \
 halui.axis.c.pos-feedback,halui.axis.u.pos-feedback,\
 halui.axis.v.pos-feedback,halui.axis.w.pos-feedback,\
 halui.axis.x.pos-feedback,halui.axis.y.pos-feedback,\
-halui.axis.z.pos-feedback \
-  keys=halui.estop.is-activated, halui.joint.0.is-homed,\
-halui.joint.1.is-homed,halui.joint.2.is-homed,halui.joint.3.is-homed,\
-halui.joint.4.is-homed,halui.joint.5.is-homed,halui.joint.6.is-homed,\
-halui.joint.7.is-homed,halui.joint.8.is-homed \
-  keys=halui.machine.is-on,halui.max-velocity.value,halui.mode.is-auto,
-halui.mode.is-manual,halui.mode.is-mdi,halui.mode.is-teleop,
+halui.axis.z.pos-feedback,halui.estop.is-activated,\
+halui.joint.0.is-homed,halui.joint.1.is-homed,halui.joint.2.is-homed,\
+halui.joint.3.is-homed,halui.joint.4.is-homed,halui.joint.5.is-homed,\
+halui.joint.6.is-homed,halui.joint.7.is-homed,halui.joint.8.is-homed,\
+halui.machine.is-on,halui.max-velocity.value,halui.mode.is-auto,\
+halui.mode.is-manual,halui.mode.is-mdi,halui.mode.is-teleop,\
 halui.program.is-running
+
 ----
 
 Note: It is recommended to use the line continuation character "\" as
 shown here to improve readability. But note that spaces must be left in
 to delimit options, and must not be included (including at the beginning
 of a line) inside a single option.
 
-HAL limits a single option/token (for example "keys=") to 255 characters.
-To work around this issue use multiple "keys=" entries as shown.
-
 == SEE ALSO
 
 hal(3hal)

src/hal/utils/halcmd.c

@@ -362,8 +362,12 @@ static int parse_cmd1(char **argv) {
 	    int i;
 	    for(i=0; i<argc; i++)
 	    {
-		char *buf = malloc(LINELEN);
-		TildeExpansion(argv[i], buf, LINELEN);
+		size_t len = LINELEN;
+		// Tilde expansion can make the string longer, so ensure
+		// there is space for that
+		while (len < strlen(argv[i]) * 2) len += LINELEN;
+		char *buf = malloc(len);
+		TildeExpansion(argv[i], buf, len);
 		argv[i] = buf;
 	    }
 	}